Oily ink for writing instrument

ABSTRACT

An oily ink for writing instruments comprising  
     e. colorant,  
     f resin,  
     g. an organic solvent and  
     h. a gelling agent,  
     wherein the said gelling agent comprises a soluble gelling agent with the solubility of form about 0.1 to about 20% by weight at a temperature of 20° C. to the said organic solvent, and the viscosity of the ink is not less than 700 mPa·s when the rate of shear is 0.1 (l/s) and not greater than 500 mPa·s when the rate of shear is 100 (l/s).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an oily ink, particularly anoily ink designed for writing instruments. The present invention relatesto a gel-type oily ink which can be suitably used for correction toolsincluding correction pens, oil-type ball-point pens, paint markers andthe like.

[0003] 2. Description of the Prior Art

[0004] Heretofore, as an oily ink for writing instruments, paint markersusing aluminum powder pigments, correction pens containing titaniumdioxide, and the like have been proposed. In addition, with regard tothe oily ink, there are various types of constructions for thecorrection pens, including pen-types, bottle-types with brush coatings,and the like. These types share the common characteristics of having astirrer made of a metallic ball built in the container in order toredisperse the colorants by stirring the ink itself. That is, in theconventional paint markers or ball-point pens, when they are left in asettled state, colorants including aluminum powder pigments or titaniumdioxide settle in the ink within the container and the functions aspaint markers or ball-point pens cannot be fully realized. Therefore, ithas been necessary for the users to redisperse the colorants that settleand separate in the container, in order to restore the initial dispersedstate.

[0005] Japanese Unexamined Patent Publication No. 6-264012 proposes acorrection fluid compounding montmorillonite-type clay mineral in orderto prevent the sedimentation of the colorants as an opacifying agent andmaintain the redispersibility of the system. Japanese Unexamined PatentPublication No. 7-173417 proposes a correction fluid compounding afluorine metallic mica.

[0006] However, in the case of such conventional oily ink compositions,sedimentation layers are sometimes formed at the bottom of the ink whenleft in a settled state for a long period of time although thecompositions prevent the colorants from settling as much as they can.Therefore there is little difference from the conventional oily ink inthat redispersion has to be considered. Moreover, and in particular,when the clay mineral or fluorine metallic mica is compounded beyond acertain level for thickening the viscosity, the ink compositions havebecome gel-type, thereby making it impossible to obtain smooth coatedfilms when coating.

[0007] Regarding this point, the same thing can be said about an oilyink composition used for oil-type ball-point pens or paint markers aswell as correction tools including correction pens and the like, and theprovision of such an oily ink as can prevent sedimentation of thecolorants while maintaining writing performance is desired in thatfield, too.

[0008] Further, in conventional oil-type ball-point pens, particularlyin ball-point pens using a white-colored oily ink, like generalball-point pens using a black-colored ink, solvents with high boilingpoint are used, thereby causing the problem of not drying when writingwith such an ink on a non-absorbent surface although when writing on anabsorbent surface like that of paper and the like, drying can be seenonly apparently. Moreover, the fact is that the fluidity is very bad andhas no practicality in coating on a surface, especially thickly on asurface.

SUMMARY OF THE INVENTION

[0009] It is, therefore, desirable to provide an oily ink compositionthat is not inclined to sedimentation and that dose not necessitateredispersion of its components. This is desirably provided by an oilyink for writing instruments comprising

[0010] a. a colorant,

[0011] b. a resin,

[0012] c. an organic solvent and

[0013] d. a gelling agent,

[0014] wherein the said gelling agent comprises a soluble gelling agentwith a solubility of from about 0.1 to about 20% by weight at thetemperature of 20° C. to the said organic solvent, and the viscosity ofthe ink is not less than 700 mPa·s when the rate of shear is 0.1(l/s)and not greater than 500 mPa·s when the rate of shear is 100(l/s)

BRIEF DESCRIPTION OF THE DRAWING

[0015]FIG. 1 is a schematic sectional view showing one embodiment of acorrection pen in accordance with the present invention.

[0016]FIG. 2 is a schematic sectional view showing another embodiment ofa correction pen in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] As a result of intensive studies for achieving the aforementioneddisered outcomes, an oily ink for writing instruments in accordance withthe present invention comprises.

[0018] a. a colorants,

[0019] b. a resin,

[0020] c. an organic solvents and

[0021] d. a gelling agents,

[0022] wherein the said gelling agent comprises a soluble gelling agentwith a solubility of from about 0.1 to about 20% by weight at thetemperature of 20° C. to the said organic solvent, and the viscosity ofthe ink is not less than 700 mPa·s when the rate of shear is 0.1(l/s)and not greater than 500 mPa·s when the rate of shear is 100(l/s).

[0023] By the foregoing, an oily ink can be obtained that is capable ofpreventing the sedimentation of the colorants including titaniumdioxide, aluminum powder pigments and the like, while maintaining a goodleveling and writing performance. Also, an oily ink can be obtained thatdose not always require one to redisperse and restir.

[0024] Soluble gelling agents as used in accordance with the presentinvention are defined as ones providing pseudo-plasticity fluidity(thixotropic property) to the min while forming a three dimensional meshstructure having the function of surface active agents capable ofpartially dissolving organic solvents (carbohydrate solvents). Examplesinclude gelling agents with the solubility at the temperature of 20° C.to organic solvents, particularly to carbohydrate solvents, is fromabout 0.1 to about 20% by weight, preferably from 0.1 to 14% by weight.

[0025] By the foregoing, levelling property and writing performance canbe displayed by the pseudo-plasticity fluidity (thixotropic property),while preventing the sedimentation of the said pigment particles bytaking the colorants, especially pigment particles including thetitanium dioxide, and the like in the foregoing dimensional meshstructure.

[0026] In accordance with the present invention, an oily ink for writinginstruments, particularly a correction ink, is provided that prevent thesedimentation of colorants, particularly opacifying pigment particlesincluding titanium dioxide by catching the colorants, especially pigmentparticles including the titanium dioxide, and the like, whilemaintaining the leveling property and writing performance, therebymaking redispersing and restirring not always necessary.

[0027] Also, in accordance with the present invention an oily ink forwriting instruments is provided that is capable of drying quickly whenwriting on a non-absorbent surface as well as a penetrating surface,including paper, and the like, and having excellence in fluidity evenwhen coating thickly on the surface.

[0028] Gelling agents to provide pseudo-plasticity fluidity includedispersible gelling agents like bentonite, and the like, but gellingagents useful in the present invention are, as previously mentioned,ones forming a three dimensional mesh structure (gel structure) in theink having the surface activity to be partially dissolved into theorganic solvents, catching the colorants into this three dimensionalmesh structure (gel structure), while lowering the viscosity by theshear force in writing process.

[0029] The aforementioned gelling agent having the desired surfaceactivity include certain types of metal soaps, but gelling agents usedin the present invention are soluble ones having a solubility of fromabout 0.1 to about 20% by weight (preferably from 0.1 to 20% by weight)in the organic solvents at the temperature of 20° C. That is, thegelling agents must be the ones having the molecular structure of polargroup and non-polar group whose solubility is from about 0.1 to about20% by weight in the organic solvents at the temperature of 20° C.,while providing the desired pseudo-plasticity fluidity property.

[0030] In such gelling agents, its three dimensional structure isestimated to have dispersal stability in the state of high viscositycatching the colorants, including pigment particles and the like, withinthe micellar structure And when a shear force is applied to the ink whenwriting, fluidization occurs with lower viscosity, thereby showing theaforementioned leveling property and writing performance.

[0031] However, when the viscosity of the ink is less than 700 mPa·swith a shear force of 0.1(l/s), the viscosity is so low that it becomesdifficult to achieve the satisfactory prevention of the sedimentation ofthe colorants, maybe because of the instability in catching thecolorants by the pigment particles even though three dimensional meshstructure is formed, thereby sometimes requiring redispersion by shakingor restirring. On the other hand, when the viscosity of the ink isgreater than 600 mPa·s with a shear force of 100(l/s), the fluiditylowers in writing, making it difficult to maintain the excellentlevelling property and writing performance.

[0032] Therefore, it is desirable for this invention to heave viscosityof not less than about 700 mPa·s with a shear force of 0.1(l/s), and notgreater than about 500 mPa·s with a shear force of 100(l/s). However,considering the above, the preferred range of the viscosity relating tothis invention is not less than about 70 mPa·s with a shear force of0.1(1/s), and not greater than 500 mPa·s with a shear force of 100(l/s),and more preferably not less than 900 mPa·s with the shear force of0.1(l/s) and not greater than 250 mPa·s with the shear force of100(1/s).

[0033] The viscosity shown in the present invention is based on theviscosity (Pa.s) when a shear force is exerted on the ink by therotation of the ball by using a correction pen having a pen-tipmaintaining the ball whose tip is 1.00 mm with a gap of 60 cm. Forexample, the viscosity shown in the present invention is one measured bythe Z20DIN rotor at a temperature of 20° C. using the reometer RS-75manufactured by HAAKE Inc.

[0034] The viscosity of this ink is desirably achieved by solublegelling agents but other viscosity modifiers can be used.

[0035] Such soluble gelling agents having these attributes can be usedin this invention. Examples include sorbitol derivatives includingdibenzylidene sorbitol and the like, dextrin fatty ester, hydrogenatedcastor oil, 1,2-hydroxystearic acid, gelling agents of polyetherester-type surfactant, and the like. As a soluble gelling agent,aluminum 2-ethylhexoate can most preferably be used. In the case ofaluminum 2-ethylhexoate, it is estimated that (1) the molecules ofaluminum 2-ethylhexoate form coordinate bonding due to the existence ofaluminum metal and (2) the three dimensional mesh structure (gelstructure) by micelle of the coordinate bond of aluminum 2-ethylhexoateis formed within the ink and (3) colorants are caught in this gelstructure, thereby preventing the sedimentation of colorants.

[0036] Further, it is considered that the oily ink, in particular, thecorrection ink compounding this aluminum 2-ethylhexoate, is attributedto the three dimensional mesh structure (gel structure) by the saidmicelle, but has the thixotropic property of having high viscosity,which lowers gradually with the rate of shear.

[0037] As aluminum 2-ethylhexoate, monosoap types and disoap types canbe cited. The composition of the present invention is not limited to anyone of the monosoap types, disoap types, and trisoap types, but to usealuminum 2-ethylhexoate of the disoap types alone or as a main componentis preferable. The reason is considered as follows. In the disoap types,due to the molecular structure of the disoap types in the system of oilyinks, it is easier to form a gel structure, and, compared to themonosoap types and trisoap types, the dispersal stability of thecolorants (including titanium dioxide, coloring pigments and the like)is particularly excellent.

[0038] The content of the soluble gelling agents in the ink compositionis not specifically limited. For example, it can be adjusted properly inaccordance with the other compounds including the content or the typesof solvents, and the like. For example, in the case of oily inkcomposition including correction liquid using cycloaliphaticcarbohydrate-type solvents, like methylcyclohexane and the like, thecontent of the selling agents like aluminum 2-ethylhexoate and the like,is preferably 0.05-5% by weight with respect to the total amount of theink from a practical point of view. And the optimum range is 0.1-3% byweight with respect to the total amount of the ink.

[0039] When gelling agents including aluminum 2-ethylhexoate arecontained in less than 0.05% by weight with respect to the total ink,the amount of compound is so little that the dispersal stability becomespoor and it is difficult to have thixotropic property since it isdifficult for the oily ink system to form the mesh structure despite theexcellence in brush coating and writing performance. On the other hand,when the gelling agents including aluminum 2-ethylhexoate is containedin greater than 5% by weight with respect to the total ink, the amountof compound is so much that the viscosity becomes too high and it isdifficult to obtain good brush coating and writing performance despitethe dispersal stability and thixotropic property of the colorants.

[0040] As for colorants, they are not specifically limited. Varioustypes of white-colored or colored pigments can be used. The examplesinclude inorganic pigments, organic pigments, resin particle pigments,fluorescent pigments, glittering pigments, light storing pigments,two-tone colored pigments, and the like. For example, as inorganicpigments or organic pigment, titanium dioxide, aluminum powder, brasspowder, alkylene bismelamine, copper phthalocyanine pigments, threnepigments, azo pigments, quinacridon pigments, anthraquinone pigments,dioxane pigments, indigo pigments, thioindigo pigments, perynonepigments, perylene pigments, indolenone pigments, azomethine pigments,and the like can be cited. And as glittering pigments, glass flakepigments metal coated pigments, and the like can be cited. As forothers, as resin particle pigments, resin particle pigments colored bypigments or dyes can be used. Further, as colorants, dyes (includingdirect dyes, acid dyes, basic dyes, and the like) can also be used.These colorants can be used either alone or in combinations of two ormore of them.

[0041] However, titanium dioxide with large specific gravity which ispoor in dispersal stability and has the strong inclination to settle andseparate at the bottom of the container in a settled state, can be usedas the most suitable colorant in carrying out the present invention. Asfor titanium dioxide, any types can be used including rutile titaniumdioxide, anatase titanium dioxide, and the like. However, in using atitanium dioxide for a correction liquid, rutile titanium dioxide withmuch opacifying property is particularly preferable.

[0042] The colorants in this invention, particularly titanium dioxide,preferably comprise from 20 to 60% by weight with respect to the inkcomposition. Particularly, in case of a correction ink, colorants asopacifying agents preferably comprise from 30 to 60% by weight withrespect to the total amount of the ink composition from a practicalpoint of view and the optimal range is from 35 to 55% by weight withrespect to the total amount of the ink composition. When colorants asopacifying agents are compounded in less than 30% by weight with respectto the total amount of the ink composition, it is difficult to obtainsatisfactory opacifying power. When the colorants as opacifying agentsare compounded in greater than 60% by weight with respect to the totalamount of the ink composition, the viscosity becomes so high that it isdifficult to obtain appropriate brush coating and writing performance.As for other colorants, at appropriate amount may be compounded inaccordance with the desired use.

[0043] As for resins which can be used in accordance with the presentinvention, such resins may be used that show the desired solubility tothe organic solvent, adhesion to the coated film forming surface orcoated surface (written surface) or the dispersibility of the colorants.That is, well known resins such as film forming resins, binder resins,dispersing resins, and the like and in particular, the ones havingcompatibility with soluble gelling agents including aluminum2-ethylhexoate, and the like. Examples include alkyl phenol resin,rosin-modified resin, alkyd resin, acryl resin, unsaturatedthermoplastic elastomer, saturated thermoplastic elastomer, vinyl alkylether resin, cyclized rubber, petroleum resin, terpene resin, and thelike. These can be selected appropriately in accordance with thecharacter and the like of the coated film and can be used either aloneor in combinations of two or more of them.

[0044] The amount of the resins to be compounded is not specificallylimited and may be decided in accordance with the concentration of thecolorants, but these resins preferably comprise in 3-30% by weight withrespect to the total amount of the ink composition and the optimal rangeis 5-20% by weight with respect to the total amount of the inkcomposition. When these resins are compounded in less than 3% by weightwith respect to the total amount of the ink composition, the fixabilityof the colorants to the coated surface lowers. When these resins arecompounded in greater than 30% by weight with respect to the totalamount of the ink composition, the viscosity becomes so high that it isdifficult to obtain appropriate brush coating and writing performance.

[0045] As for organic solvents, ones which can achieve the solubility ofthe said resins and dryness of the coated films can be used. Forexample, hydrocarbon solvents including aliphatic hydrocarbon solvents,alicyclic hydrocarbon solvents aromatic hydrocarbon solvents,halogenetad hydrocarbon solvents, and the like can be used. In addition,polar solvents including alcohol solvents such as methyl alcohol, ethylalcohol, propyl alcohol, and the like; ketone solvents including methylethyl ketone, methyl isobutyl ketone, and the like and alcohol ethersolvents including propylene glycol monomethyl ether, propylene glycoldimethyl, and the like can be used.

[0046] However, in an oily ink composition compounding aluminum2-ethylhexoate, as organic solvents, hydrocarbon solvents includingaliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatichydrocarbon solvents, halogenated hydrocarbon solvents, and the like canbe preferably used. This is because in the case of hydrocarbon solvents,particularly of aliphatic hydrocarbon solvents, alicyclic hydrocarbonsolvents, aromatic hydrocarbon solvents, halogenetad hydrocarbonsolvents, the said three dimensional mesh structure (gel structure) caneasily be formed thereby enabling the appearance of a prevention effectagainst the sedimentation and separation of the colorants fully contraryto the alcohol solvents including propyl alcohol and ketone solventsincluding methyl ethyl ketone in which the said three dimensional meshstructure (gel structure) by the micelle is hard to be formed in theink. On the other hand, in soluble gelling agents includingdibenzylidenesorbitan and the like, the said three dimensional meshstructure (gel structure) can easily be formed in alcohol solventsincluding propyl alcohol, and the like or alcohol ether solvents,thereby enabling the appearance of a satisfactory preventative effectagainst the sedimentation and separation of the colorants.

[0047] In the case of oily ink composition in this invention compoundingsoluble gelling agents including aluminum 2-ethylhexoate and the like,cyclohexane, methyl cyclohlexane, ethyl cyclohexane, cyclopentane canpreferably be used among alicyclic hydrocarbon solvents as an eraserliquid from the viewpoint of being difficult to dissolve the writinglines and of dryness, but what is more important is that such solventsshould also provide the environment to easily form the three dimensionalmesh structure (gel structure) in the system against the soluble gellingagents like aluminum 2-ethylhexoate.

[0048] For example, the same can be applied to aliphatic hydrocarbonsolvents, particularly to iso-heptane, n-heptane, iso-octane, n-octane,and the like.

[0049] As for organic solvents, quickly drying organic solvents arepreferably used. In particular, when such quickly drying organicsolvents whose vapor pressure is at least 20 mm Hg, preferably 20-300mmHg (20° C.), are used in the oily ink in this invention, particularlyin the correction ink in this invention wherein the ink compositioncontains opacifying pigments including titanium dioxide and the like,since the pseudo-plasticity fluidity property is given to the ink,fluidity is shown when writing but after writing quickly dries losingthe fluidity, it can be instantly written again on the opacifyingsurface. Therefore, they are preferable as correction inks.

[0050] These organic solvents include, in addition to cyclohexane,methyl cyclohexane, ethyl cyclohexane, cyclopentane as previouslymentioned, iso-hexane, iso-heptane, iso-octane, and n-octane can becited. However, in view of quick dryness and pseudo-plasticity fluidityof the gelling agents, cyclohexane, methylcyclohexane, ethylcyclohexane,cyclopentane are preferable; particularly methylcyclohexane ispreferable.

[0051] On the other hand, in dissolving soluble gelling agents likealuminum 2-ethylbexoate to, for example, alicyclic hydrocarbon solvents,by adding a little amount of alcohol (particularly methyl alcohol orethyl alcohol), aluminum 2-ethylhexoate becomes easily dissolved.

[0052] That is, soluble gelling agents having polar group and non-polargroup in the molecule becomes easy to dissolve by combining low polar(or non-polar) solvents and polar solvents. Also, by combining low polar(or non-polar) solvents and polar solvents, such soluble gelling agents,particularly for aluminum 2-ethylhexoate, easily form three dimensionalmesh structure (gel structure) within its system.

[0053] To be concrete, the compounding ratio of the alcohol solventsincluding methyl alcohol, ethyl alcohol, isopropyl alcohol and the liketo gelling agents is preferably 1 part by weight to 5 parts by weight.If alcohol solvents are compounded at greater than 5 parts by weight to1 part by weight of gelling agents, even if alicyclic hydrocarbonsolvents are compounded, a three dimensional mesh structure (gelstructure) is not formed easily by the gelling agents including aluminum2-ethylhexoate.

[0054] In the case of organic solvents, particularly of hydrocarbonsolvents including aliphatic hydrocarbon solvents, alicyclic hydrocarbonsolvents, aromatic hydrocarbon solvents, halogenetad (hydrocarbonsolvents, the content is preferably 10-70% by weight with respect to thetotal amount of weight with respect to the total amount of the ink.

[0055] When the content of these solvents is less than 10% by weightwith respect to the total amount of the ink, the viscosity becomes sohigh that appropriate brush coating and writing performance is hard toobtain. On the other hand, when the content of these solvents is greaterthan 70% by weight with respect to the total amount of the ink, theopacifying property by colorants lowers and in the case of usingcolorants as opacifying agents, the practicality deteriorates.

[0056] For example, various types of dispersions and surface activeagents in addition to fine silica flours to improve the coating andplastic pigments to adjust the flow property can be added.

[0057] Particularly, in the case of an oily ink in accordance with thepresent invention comprising a nonionic type surface-active agent,compared with an oily ink not containing said surface-active agent,dispersal stability of the colorants, particularly of the pigmentparticles, particularly of the pigment particles of a titanium dioxideand the fluidity of the ink can be further enhanced. This nonionic typesurface-active agent is not specially limited, but higher alcoholethylene oxide addition products, alkylphenol ethylene oxide additionproducts, and sorbitan aliphatic acid ester are preferable. As higheralcohol ethylene oxide addition products, polyethylene lauryl ether, andpolyoxyetlylene stearyl ether can be cited. As alllphenol ethylene oxideaddition products, polyoxyethylene nonyl phenyl ether andpolyoxyethylene octyl phenyl ether can be cited. As sorbitan aliphaticacid ester, sorbitan monolaurate, sorbitan monooleate, sorbitantrioleate can be cited. In addition, the nonionic type surface-activeagent preferably comprise from 0.3 to 5% by weight with respect to thetotal amount of the ink.

[0058] As above-mentioned, since the gel-type oily ink in accordancewith the present invention can show excellent leveling property and canprevent the sedimentation of the colorants, while maintaining the brushcoating and writing performance, it can be used for various types ofwriting instruments whether they are press-type or non-press-type,including oil-type ball-point pens and paint markers, in particular,erasers including correction pens and brush coating type correctionliquid and the like.

[0059] For example, the gel-type oily ink in accordance with the presentinvention can be used for the correction pen 1 shown in the FIG. 1. Thiscorrection pen 1 contains an oily ink 12 in an ink containment tube 11related to the present invention showing pseudo-plasticity fluidity.This oily ink 12 can contain all types of inks as far as they are inaccordance with the present invention, while the correction pen 1 inthis embodiment can preferably used for a quickly drying correction inkcomprising titanium dioxide as an opacifying white pigment and a quicklydrying organic solvent as an organic solvent. As shown in the FIG. 1, onan ink outflow part 14 at one end of the ink containment tube 11 of thiscorrection pen 1, a rod type pen tip 13 comprising of filters orplastics is attached. In addition, at the other end of the inkcontainment tube 11 having a bottom, a pressurizing device 15pressurizing this said ink containment tube 11 is attached. Further,over this correction pen 1, a coverage structural body 16 is fitted toprevent the evaporation of quickly drying solvent contained in the oilyink 12 and to prevent dryness of the pen tip 13. For example, the inkcontainment tube 11 of this correction pen 1 is composed of atransparent or semi-transparent synthetic resin material. And in thisembodiment, unlike a conventional correction pens or a brush coatingtype correction bottle, no stirrer is contained in the ink containmenttube 11.

[0060] Further, for example, a gel-type oily ink in accordance with thepresent invention can be used for a correction pen 2 shown in the FIG.2. In this correction pen 2, an ink containment tube 21 is charged in anouter cylinder 20 and an oily ink 22 related to this invention showingthe pseudo-plasticity fluidity in the ink is contained in the inkcontainment tube 21. This oily ink 22 can also contain all types of inksas far as they are oily inks in accordance with the present invention,while the correction pen 2 in this embodiment can also preferably beused for a quickly drying correction ink comprising titanium dioxide asan opacifying white pigment and a quickly drying organic solvent as anorganic solvent. As shown in FIG. 2, on an ink outflow part 23 at oneend of the ink containment tube 21 of this correction pen 2, a pen tip24 composed of a ball is attached to a socket 25. Also in the inkcontainment tube 21 of this correction pen 2, an ink follower 26 iscontained in such a way that it attaches to the said oily ink 22 forpreventing the back flow of the ink and the evaporation of the organicsolvent. This ink follower 261 composed of at least a first layer 261touching the said oily ink 22 and a second layer 262 touching the firstlayer 261. And the said first layer 26 is composed of an aqueousgel-type substance containing a water-soluble polymer as a selling agentand the said second layer 262 is composed of an organic liquid withinvolatile or nonvolatile property. Since the oily ink 22 contained inthis writing instrument is a quickly drying gel-type oily ink havingpseudo-plasticity fluidity whose viscosity of the oily ink 22 containedin this writing instrument is not less than 700 mPa·s when the rate ofshear is 0.1 (l/s) and not greater than 250 mPa·s when the rate of shearis 100 (l/s), It is important for the ink follower 26 to show thepseudo-plasticity fluidity depending on the said viscosity change withthe outflow of this ink contacting with the said oily ink when this oilyink 22 flows out of the pen tip with thinning shear in writing, and toshow the pseudo-plasticity fluidity suppressing the evaporation of thequickly-drying organic solvent. In this regard, in this writinginstrument, the said aqueous gel-type substance is used as the firstlayer 261 and, particularly, in order to achieve the said requirement,as a gelling agent of the aqueous gel-type substance, saccharidesincluding xanthane gum, welan gum, rhamean gum, succinoglycan, gelangum, and the like, celluloses including carboxymethyl cellulose,hydroxyethyl cellulose, and the like, synthetic water-soluble polymersincluding polyvinyl alcohol, polyacrylic acid sodium and the like, arepreferably used. In addition, in order to further ensure to the meetingof the said requirement, this writing instrument provides at least thesecond layer 262 contacting with the first layer 261. The said secondlayer 262 is composed of involatile or non-volatile organic liquid orgelatinized organic liquid. And as this organic liquid, polybutene andthe like can be preferably used other than silicone oil. Further, inparticular, in the case of this embodiment, since it uses oily inkcontaining quickly drying organic solvent, in order to ensure theprevention of dryness of the ink and the evaporation of the organicsolvent, as shown in the FIG. 2, at the pen tip 24 of a ball in thedirection of the outflow of the ink, the energizing force of a spring isprovided and at the inner bottom of the cap 3, an elastic body 31 isprovided to which the ball of this pen tip 24 adheres repulsively by theenergizing force of a spring. As the elastic body 31, hotmelts, siliconeballs, rubber caps, and the like can be used, For example, 26 is an inkoutflow part conducting the oily ink 22 in the ink containment tube 21to the direction of the pen tip 24, and in this writing instrument, aback flow preventive valve is provided in the ink outflow part 26. Also,in this writing instrument, a back flow preventive body 27 is charged.Further, at the end of the outer cylinder 20 at the other end of the inkcontainment tube 21, a dryness-preventing agent 28 is packaged therein.As a dryness-preventing agent 28, for example, grease-type substance inwhich a quickly drying solvent is gelatinized is preferable. Forexample, a float 29 is set in the ink follower. For a further example,both the ink containment tube 21 and the outer cylinder 20 of thiscorrection pen 2, similar to the said embodiment, are composed of atransparent or semi transparent synthetic resin material. And theembodiment also refers to the correction pen without the need ofstirring and shaking without any stirrer in the ink containment tube 21,unlike conventional correction pens or brush coating-type correctionbottle products.

[0061] Since any of such correction pens as mentioned above containsgel-type oily ink with excellent dispersal stability, unlike theconventional correction pens or brush coating-type correction bottleproducts, it can flow out ink and write without shaking or stirring by astirrer. Also, when the writing process is stopped, since the outflowingink loses fluidity and dries immediately, no problem occurs, includingthe outflow, blurring of the ink or the thickening of the tip of thecoated film, and the like even when it is coated thickly on paper,thereby showing particular excellence in leveling property and rewritingperformance, such as over-writing performance. Also, since the oily inkin accordance with the present invention is a pseudo-plasticity fluiditybody that is excellent in dispersal stability and can prevent theseparation and sedimentation of colorants, the oily ink can be containedin a transparent or semi-transparent ink containment tube or the outercylinder, thereby realizing the good product value including the goodlooking appearance and the like. Further, it has the advantage of beingcapable of providing visual observation of the residual amount of theink from the outside of the writing instrument.

[0062] The oily ink in accordance with the present invention cannot berestrictively applied to the said correction pen. For example, theconfiguration or the structure of the pen tip can be applied to cylinderbodies (rollers) in addition to balls and rods (including chips).Further, it can be also applied to a writing instrument having a pen tipholding a several pen-tip structure selected from balls, rods, andcylinder bodies. Also, in accordance with the present invention, as ameasure to prevent the dryness of the ink and the evaporation of theorganic solvent, any adhesion measures may be included as far as theyare ones to adhere to the structure of the ink outflow part includingthe pen-tip other than the method mentioned in the said embodiment.Further, in the case of the said embodiment, although the inkcontainment tube and the outer cylinder are composed of a transparent orsemitransparent synthetic resin material, various types of the materialsincluding the transparent or semitransparent glass materials ornontransparent synthetic resin materials or glass materials can be used.In addition, the ink containment tube can have the bottom as in a saidembodiment or without the bottom as in a refilling type.

[0063] The said embodiment refers to a correction pen, however, it canbe applied to paint markers or oil-type ball-point pens. Further, it canbe applied for the correction tools with a bottle type brush coatings.For information, in the case of the oily ink including the quicklydrying organic solvents, the most preferable is to apply for thecorrection pens, paint markers, and the oil-type ball-point pens whosestructure can contain the oily ink in the closed space.

EXAMPLES Example 1 and Comparative Examples

[0064] The oily ink compositions of the present invention in theExamples (Table 1) and the other oily ink compositions in theComparative Examples (Table 2) were prepared according to thecompounding compositions shown in the Tables. First, resins were heatedand dissolved into methylcyclohexane, the organic solvent. Thereafteralcohol as a solution aiding agent, was added. Next, soluble gellingagents (where indicated) were added and made into solution by thoroughlystirring with the dissolver, thereby preparing resin liquid containingsoluble gelling agents.

[0065] Next, titanium dioxide or aluminum powder pigment as thecolorant, and the said resin liquid were mixed and after completekneading, dispersion disposal was made using a heretofore knowndispering machine, thereby obtaining the specific oily ink. Forinformation, the compounds shown in the Tables are represented by partsby weight. TABLE 1 (parts by weight) Example 1 2 3 4 5 6 7 8 9 Titaniumdioxide A 50 25 50 50 50 B 25 C 50 50 Aluminum powder pigment 4 Gelling2-aluminum ethylhexoate 2 2 2 2 1.2 1.5 1.5 1.2 1.5 agent Aluminumstearate Bentonite Alkyl phenol resin 18 7 20 2.5 3 6 2 Rosin-modifiedphenol resin 4 0.5 Alkyd resin 10 Nonion type A 1 1 2.5 surface-activeagent B 1 1 Solvent Methylcyclohexane 30 65 70 70 43.5 42.5 39.5 43.5 34Ethylalcohol 2 2 2 3 1.8 2 2 1.8 2 Solubility of gelling agent to thesolvent 14 10.1 9.8 12.1 11.9 12.5 12.9 11.9 13.6 (% bw) Viscosity (mPa· s) Rate of shear 0.1 (l/s) 7500 4900 6300 1500 900 1400 2500 1100 5700Rate of shear 100 (l/s) 450 290 350 80 80 120 140 100 240 Fluidity ofthe Ball diameter 1.5 mm I I I I I I I I I ink Ball diameter 1.0 mm IIII II II I I I I I Ball diameter 0.5 mm II II II II II I I I I Levelingproperty I I I I I I I I I Writing performance I I I I I I I I I Drynessof the coated film I I I I I I I I I Dispersal stability Preserved 1week I/I I/I I/I I/I I I I I I at room 2 weeks I/I I/I I/I I/I I I I I Itemperature 1 month I/I I/I I/I I/I I I I I I 2 months I/I I/I I/I I/I II I I I Preserved 1 week I/I I/I I/I I/I I I I I I at 40° C. 2 weeks I/II/I I/I I/I I I I I I 1 month I/I II/II I/I II/II I I I I I 2 monthsII/II II/II II/II II/II I I I I I

[0066] TABLE 2 (parts by weight) Comparative Example 1 2 3 4 5 6 7Titanium dioxide A 50 25 50 50 50 B C 50 Aluminum powder pigment 4Gelling 2-aluminum ethylhexoate 1 1.5 agent Aluminum stearate 2Bentonite 2 Alkyl phenol resin 18 20 18 18 2 6 Rosin-modified phenolresin 4 Alkyd resin Nonion type A 1 surface-active agent B 2.5 SolventMethylcyclohexane 30 70 72 30 30 44.6 38 Ethylalcohol 2 2 3 2 2 1.4 2Solubility of gelling agent to the 14 9.8 11.9 10.6 0 10.2 13.2 solvent(% bw) viscosity (mPa · s) rate of shear 0.1 (l/s) 60 30 25 20 3600 360210 rate of shear 100 (l/s) — — — — 210 70 70 Fluidity of the Balldiameter 1.5 mm I I I I II I I ink Ball diameter 1.0 mm I I I I II I IBall diameter 0.5 mm I I I I II I I Leveling property I I I I I I IWriting performance I I I I I I I Dryness of the coated film I I I I I II Dispersal stability Preserved 1 week III/III II/I III/III III/IIIIII/III I I at room 2 weeks III/III III/III III/III III/III III/III I IItemperature 1 month III/III III/II III/III III/III III/III II III 2months III/III III/III III/III III/III III/III II III Preserved 1 weekIII/III II/II III/III III/III III/III I I at 40° C. 2 weeks III/IIIIII/II III/III III/III III/III II II 1 month III/III III/II III/IIIIII/III III/III III III 2 months III/III III/III III/III III/III III/IIIIII III

[0067] In the Tables,

[0068] Titanium dioxide A is manufactured by Titan Kogyo Co., Ltd. underthe trade name of Kronos KR-270,

[0069] Titanium dioxide B is manufactured by Titan Kogyo Co., Ltd. underthe trade name of Kronos KR-380N,

[0070] Titanium dioxide C is manufactured by Ishihara Sangyo K.K. underthe trade name of R-930,

[0071] Aluminum powder pigment is manufactured by ECKART-WERKE under thetrade name of HYDROLAC BGH CHROM X,

[0072] Aluminum 2-ethylhexoate is manufactured by HOPE CHEMICAL CO.,LTD., under the trade name of OCTOPE Al-A,

[0073] Alkylphenol resin is manufactured by Arakawa Chemical IndustriesLtd., under the trade name of TAMANOL 510

[0074] Rosin-modified resin is manufactured by Arakawa ChemicalIndustries Ltd., under the trade name of TAMANOL 135

[0075] Alkyd resin is manufactured by Arakawa Chemical Industries Ltd.,under the trade name of Arakyd 6701-60

[0076] Noruonic surface active agent A is manufactured by KaoCorporation under the trade name of RHEODOLSP-010

[0077] Nonionic surface active agent B is manufactured by KaoCorporation under the trade name of EMULGEN 105

[0078] For information, in the Tables, the solubility of the solublegelling agents to the organic solvent (20° C.) is represented by thesolubility (% by weight) of each soluble gelling agent tomethlylcyclohexane and ethyl alcohol. The large value of solubilityshows that the soluble gelling agents can easily be dissolved and asshown in the Comparative Example 5, if the solubility equals to 0,

[0079] it shows that the soluble gelling agents are not dissolved to thesolvent but disperse. In addition, in the Table, the viscosity is shownbased on the viscosity (mPa·s) with the shear force added to the ink bythe rotation of a ball using the correction pen shown in the said FIG. 2having the pen-tip with a ball whose diameter at the top end is 1.0 mmholding the gap of 60 μM.

[0080] Next, the oily ink in the Examples 1-4 and the ComparativeExamples 1-5 were put into glass bottles and the (dispersal stability)was evaluated at room temperature and at the temperature of 40° C. overtime. Each of the evaluation items is as follows and in the Tables, theevaluation is represented by (the concentration of the top layer/thesedimentation amount at the sublayer).

[0081] (The Concentration of the Top Layer)

[0082] The component of the top layer (supernatant liquid) of the oilyink in the glass bottle was stripped with a dropping pipette, coated onthe black paper and evaluated. I is for the one which is the same as theinitial state of the evaluation, II is for the one which is thinnercompared with the said initial state of the evaluation, and III is forthe one which is the state where nothing appears on the paper.

[0083] (The Sedimentation Amount at the Sublayer)

[0084] The evaluation was relatively made by the amount of the cakeraked by a spatula of the sublayer of the oily ink in the glass bottle.I is for the one which has little cake, II is for the one which has somecake, and III is for the one which has much cake.

[0085] Also, the oily ink in the Examples 5-9 and the ComparativeExamples 6-7 were evaluated on stability at a settled state (dispersalstability) over time, and the whole appearance of the ink was observedfrom the top layer to the sublayer. In the Tables, I is for the onewhich is the same as the initial state of the evaluation, II is for theone in which sedimentation is seen compared with the said initial stateof the evaluation, and III is for the one in which sedimentation isclearly seen.

[0086] Next, in the Tables, organoleptic evaluation was maderespectively on the fluidity of the ink (the amount of the outflowingink).

[0087] The oily ink in the each Example and Comparative Example wascontained in the ink containment tube of the correction pen shown in thesaid FIG. 2 having a pen tip holding the ball whose diameter at the pentip is 0.5 mm, 1.0 mm, and 1.6 mm with the gap of 30 μm, 60 μm, and 90μm respectively and then written on black paper and evaluated.

[0088] I is for the one which is excellent, II is for the one which isgood, and III is for the one which is not good.

[0089] Further, in the Table, organoleptic evaluation was maderespectively on the leveling property, writing performance, and thedryness of the coated films. The oily ink in the each Example andComparative Example was contained in the ink containment tube of thecorrection pen shown in the said FIG. 2 having a pen tip holding theball whose diameter at the pen tip is 1.0 mm and written on the blackpaper and evaluated.

[0090] I is for the one which is excellent, II is for the one which isgood, and III is for the one which is not good.

[0091] For information, all correction pens used for the said variousevaluations have the structure shown in the FIG. 2 and all of them usethe ball-point pen tips made of stainless (the material of the ball:carbide alloy).

[0092] From the Tables, the ink in accordance with the present inventionin the Examples was good in any respect of the fluidity, dispersalstability, leveling property, writing performance, and dryness of theink. Particularly, in the case of the oily ink in the Examples 5-9further compounding with nonionic surface-active agent, compared withthe ink not compounding with nonionic surface-active agent, the fluidityand the dispersal stability of the ink was recognized to be enhanced agreat deal by the effect of the said surface-active agent even when theresin compounding amount is little.

[0093] This invention can, as previously mentioned, prevent thesedimentation of the colorants, while maintaining a good levelingproperty, brush coating and writing performance in the case of an oilyink, particularly of the correction ink. Therefore, this invention canprovide a correction pen which can be applied without redispersing orrestirring. In addition, particularly, in the case of an oily ink havingpseudo-plasticity fluidity containing opacifying pigments includingtitanium dioxide and quickly-drying organic solvent, extremely excellentcorrection ink can be obtained in that smooth rewriting surface appearseven when written thickly because, when the writing process on the paperand the like stops, it dries instantly, while losing the fluidity.

[0094] Therefore, the oily ink composition of the present invention canpreferably be used for a correction ink but further can be applied foran ink for oily ball-point pens and an ink for paint markers as well.

What is claimed is:
 1. An oily ink for writing instruments comprising a.colorants, b. resins, c. an organic solvent and d. a gelling agent,wherein the said gelling agent comprises a soluble gelling agent withthe solubility of from about 0.1 to about 20% by weight at a temperatureof 20° C. to the said organic solvent, and the viscosity of the ink isnot less than 700 mPa·s when the rate of shear is 0.1 (l/s) and notgreater than 500 mPa·s when the rate of shear is 100 (l/s).
 2. An oilyink for writing instruments as set forth in claim 1, wherein theviscosity of the ink is not less than 900 mPa·s when the rate of shearis 0.1 (l/s) and not greater than 250 mPa·s when the rate of shear is100 (l/s).
 3. An oily ink for writing instruments as set forth in claim1, wherein said colorant comprises titanium dioxide.
 4. An oily ink forwriting instruments as set forth in claim 3, wherein titanium dioxide ispresent in an amount from about 20 to about 60% by weight with respectto the total amount of the ink.
 5. An oily ink for writing instrumentsas set forth in claim 1, wherein said gelling agent comprises aluminum2-ethylhexoate.
 6. An oily ink for writing instruments as set forth inclaim 1, wherein said gelling agent comprises disoap-type aluminum2-ethylhexoate.
 7. An oily ink for writing instruments as set forth inclaim, wherein said gelling agent is present in an amount from about0.05 to about 5% by weight with respect to the total amount of the ink.8. An oily ink for writing instruments as set forth in claim 1, whereinsaid organic solvent comprises a hydrocarbon solvent.
 9. An oily ink forwriting instruments as set forth in claim 1, wherein said organicsolvent comprises a quick-drying organic solvent having a vapor pressureof at least 20 mmHg (20° C.).
 10. An oily ink for writing instruments asset forth in claim 8, wherein said organic solvent comprisesmethylcyclohexane.
 11. An oily ink for writing instruments as set forthin claim 1, wherein said organic solvent is present in an amount fromabout 10 to about 70% by weight with respect to the total amount of theink.
 12. An oily ink for writing instruments as set forth in claim 1,wherein said resin comprises an alkylphenol resin, a rosin-modifiedresin, or an alkyd resin.
 13. An oily ink for writing instruments as setforth in claim 1, wherein said resin is present in an amount from about3 to about 30% by weight with respect to the total amount of the ink.14. An oily ink for writing instruments as set forth in claim 1, furthercomprising a nonionic surface-active agent.
 15. An oily ink for writinginstruments as set forth in claim 14, wherein said nonionicsurface-active agent comprises a higher alcohol ethylene oxide additionproduct, an alkylphenol ethylene oxide addition product, or a sorbitanaliphatic acid ester addition product.
 16. An oily ink for writinginstruments as set forth in claim 14, wherein said nonionic surfaceactive agent is present in an amount from 0.8 to about 5% by weight withrespect to the total amount of the ink.
 17. A writing instrumentcontaining an oily ink as set forth in claim
 1. 18. A writing instrumentas set forth in claim 17, wherein the oily ink set forth in claim 1 iscontained in an ink containment tube of said writing instrument, and atone end of the said ink containment tube is attached a pen tip, and anink follower is so contained in the said ink containment tube as to comein contact with the said oily ink, and the said ink follower is composedof at least a first layer that comes in contact with the oily ink and asecond layer that comes in contact with said first layer, and said firstlayer is aqueous gel-type substance and said second layer is an organicliquid with an involatile or a nonvolatile property.
 19. A writinginstrument as set forth in claim 18, wherein said aqueous gel-typematerial comprises a water-soluble polymer as a gelling agent.
 20. Awriting instrument as set forth in claim 19, wherein said water solublepolymer comprises a polysaccharide.
 21. A writing instrument as setforth in claim 17, wherein the writing instrument comprises at least anyone of a ball, a roller and a rod at an ink outflow part at a pen tip.22. A writing instrument as set forth in claim 21, wherein said ink canbe visually observed from outside said writing instrument.
 23. A methodusing of a correction pen as set forth in claim 21 comprising opacifyinga misspelling by writing on the misspelling without shaking or stirringsaid correction pen.